Apparatus and method for coating organic film

ABSTRACT

An apparatus and method for coating an organic film are disclosed. The apparatus comprises an evaporation device, an electron emission device and a spray device; wherein the evaporation device comprises an evaporation container, the evaporation container is a linear evaporation container, in which a uniform organic gas is generated; the electron emission device is horizontally arranged over the evaporation container such that the organic gas evaporated in the evaporation container is uniformly charged and becomes charged organic gas; the spray device is provided with an electric field, under which the charged organic gas is moved toward a substrate so as to deposit the organic film on the substrate.

FIELD OF THE ART

Embodiments of the present invention relate to a filed of manufacturingan active matrix organic light emitting diode, particularly relates toan apparatus and a method for coating an organic film.

BACKGROUND

OLED (Organic Light Emitting Diode) display, which is provided with anextremely thin organic material coating and a glass substrate, canachieve self-illumination, since the organic material may illuminatewhen the current pass through it. The OLED display has attractedconsiderable attention duo to the advantages such as wide viewing angel,significant power saving, simple structure and high quality dynamicpicture.

Currently, the OLED display is gradually mass produced. Particularly,the research on the large size AMOLED (Active Matrix Organic LightEmitting Diode) display is becoming a hotspot, and then the EL(electroluminescent) module used in AMOLED display is also becoming amain research object. In the conventional process, organic film used inthe luminescent layer of the EL module is formed by evaporation . Inconventional evaporation process, the evaporation source is a singlepoint source, from which the organic molecules are gasified orsublimated without directionality. The proportion of the material coatedon the substrate to the material evaporated is very low, because manysublimated molecules are attached to the evaporation chamber rather thanon the substrate. Moreover, it is difficult to form a uniform film bythe single point source, because the distance between the evaporationsource and the coating position varies with the change of the coatingposition on the substrate.

It is required to provide an evaporation apparatus by which a large areaorganic film can be formed with high accuracy, because the uniformity ofthe film has a great influence on the brightness and the chromaticity ofluminescence. In the conventional technology, an apparatus for coating alarge area film comprises: a container 24, an evaporated steam flowadjustor 25 and a top plate 26 (as shown in FIG. 1). In addition, theapparatus further comprises a heating device (not shown in FIG. 1). Theevaporated steam flow adjustor 25 has a porous layered structure and isdisposed between the container 24 and the top plate 26. The evaporatedsteam flow adjustor 25 is used to control the flow and the direction ofthe evaporated steam and enlarging the steam distribution area, so as tospray the steam uniformly onto the substrate for providing a planar filmformed of sprayed spots. The overlapped deposition area of spray nozzles261 can be adjusted by changing the distribution and diameter of thespray nozzles 261. However, because the accuracy of deposition cannot beimproved by above apparatus and process, the serious waste of organicmaterial has not been avoided and the deposition rate has not beenimproved yet.

Therefore, selecting for appropriate organic materials and designing amore efficient deposition apparatus, which are beneficial to improve theutilization and the accuracy of the organic materials deposition, becomethe focus of researcher and manufactory. However, during theconventional process for coating an organic material, the depositedpattern is significantly deformed and is not uniform at all due to thedimensional error and the low accuracy of the mask, thus, the pixelcrosstalk and short circuit may occur, the deposition accuracy and thedefect-free rate may be further decreased.

SUMMARY

Embodiments of the invention provide an apparatus and a method forcoating an organic film, by which the organic material can be uniformlydeposited onto the substrate, so as to improve the deposition accuracyand deposition rate, realize the uniformity of the film thickness,enhance the utilization of the organic material, and avoid the waste ofthe organic material.

According to a first aspect of the invention, it is provided anapparatus for coating an organic film comprising an evaporation device,an electron emission device and a spray device;

wherein said evaporation device comprises an evaporation container, saidevaporation container is a linear evaporation container, in which auniform organic gas is generated;

said electron emission device is horizontally arranged over theevaporation container such that the organic gas evaporated in theevaporation container is uniformly charged and becomes charged organicgas;

said spray device is provided with an electric field, under which thecharged organic gas is moved toward a substrate so as to deposit theorganic film on the substrate.

According to a second aspect of the invention, it is provided a methodfor coating an organic film, comprising:

heating and evaporating an organic material to generate uniform organicgas;

uniformly charging the uniform organic gas for obtaining charged organicgas; and

accelerating and moving the charged organic gas toward the substrateunder an effect of an electric filed to form the organic film on thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to clearly illustrate the technical solution of the embodimentsof the invention, the drwings of the embodiments will be brieflydescribed in the following; it is obvious that the described drawingsare only related to some embodiments of the invention and thus are notlimitative of the invention.

FIG. 1 is a view schematically illustrating an apparatus for evaporatingan organic material in conventional technology;

FIG. 2 is a view schematically illustrating an apparatus for evaporatingan organic film provided by a first embodiment of the present invention;

FIG. 3 is a cross-section view schematically illustrating chargedorganic gas which is deposited from a spray chamber onto a surface of asubstrate in the first embodiment of the present invention;

FIG. 4 is a three dimension (3D) view schematically illustrating anapparatus for coating an organic film and a movable substrate providedby the first embodiment of the present invention;

FIG. 5 is a flow chart illustrating a procedure of a method for coatingan organic film provided by a second embodiment of the presentinvention;

FIG. 6 is a flow chart illustrating step S1 in the method for coating anorganic film of the second embodiment of the present invention;

FIG. 7 is a flow chart illustrating step S3 in the method for coating anorganic film of the second embodiment of the present invention.

Reference Numerals:

1-heating source 2-organic material 3-evaporation container 4-barrier5-electron emission device 6-insulator 7-electrode plate 8-spray chamber9-gas channel 10-sidewall of the spray chamber 11-spray head 12-mask13-substrate 14-platform 15-evaporation opening 24-container25-evaporated steam flow adjustor 26-evaporation top plate 261-spraynozzle 91-evaporation device 92-spray device.

DETAILED DESCRIPTION

In order to make objects, technical details and advantages of theembodiments of the invention apparent, the technical solution of theembodiment will be described in a clearly and fully understandable wayin connection with the drawings related to the embodiments of theinvention. It is obvious that the described embodiments are just a partbut not all of the embodiments of the invention. Based on the describedembodiments herein, those skilled in the art can obtain otherembodiment(s), without any inventive work, which should be within thescope of the invention.

First Embodiment

The first embodiment of the present invention provides an apparatus forcoating an organic film , which comprises an evaporation device 91, anelectron emission device 5 and a spray device 92, as shown in FIG. 2.

The evaporation device comprises an evaporation container 3. Theevaporation container 3 is a linear evaporation container whichgenerates uniform organic gas. The so-called “linear” evaporationcontainer is the container in which the uniform organic gas can begenerated under the heat of a linear heating source. The evaporationcontainer 3, in which an organic material 2 is contained, is typicallymade of the stainless steel.

The evaporation device further comprises a heating source 1, which maybe a linear heating source or a plurality of heating sources parallel toeach other. The heating source 1 arranged at the bottom of theevaporation container 3 heats the organic material 2 disposed in theevaporation container 3 to provide the heat for evaporating the organicmaterial 2. For example, the heating source 1 may consists of coils, andan AC voltage from an AC power source at outside of the evaporationcontainer 3 is applied to the coils with a given frequency, which canaccurately control the heating temperature, so as to ensure the organicmaterial is heated uniformly.

The evaporation container 3 is the linear evaporation container with aslit-like evaporation opening 15 at the top of the evaporation container3. In one example, a cooling pipe is arranged around the evaporationcontainer 3 (not shown in FIG. 2). The cooling pipe is filled withcirculating refrigerant (such as gas) to maintain the temperature of theevaporation container 3, so that the occurrence of thermal cracking andchemical reaction of the organic material can be suppressed.

The electron emission device 5 is horizontally arranged over theevaporation container 3 and emits the electron “e”. The electronemission port of the electron emission device 5 is arranged over theevaporation opening 15, so that the organic gas evaporated from theevaporation opening 15 is uniformly charged and becomes the chargedorganic gas (represented by “Q” in FIG. 2). By moving a movable barrier4 (such as push-pull type barrier) arranged at a side of the evaporationopening 15, the evaporation opening 15 can be opened or closed, suchthat the amount of the organic gas evaporated from the evaporationcontainer 3 is controllable. The barrier 4 can be manipulated to closethe evaporation opening while the deposition process is not necessary.Because the organic material still keeps being evaporated under theresidual heat of the heating source, the organic material may be wasted.Therefore, it is preferable to provide a barrier that closes theevaporation opening in time in order to improve the utilization of thematerial and save the cost.

The electron emission device 5 is horizontally arranged over theevaporation container 3. The electron emission device 5 may be a linearelectron gun or a plurality of small-sized electron guns arranged withequal interval and emits the electrons uniformly. The electrons attachto the organic gas, thus the organic gas is charged uniformly andsufficiently. The energy of the electrons emitted from the electron gunshould not be too high to avoid damage the organic material. Theelectron gun may be a thermionic emission tungsten cathode electron gunor a cold cathode field emission electron gun. However, the method forcharging the organic gas is not limited to the above embodiment, forexample, the organic gas can also be charged by positive charge.

Using the electron emission device 5, the charged organic gas Q isobtained by uniformly charging the organic gas evaporated from theevaporation container 3.

In the spray device 92, the charged organic gas Q moves to the substrate13 under the effect of electric filed so as to form an organic film onthe substrate 13. For example, the spray device may comprise electrodeplate 7, a spray chamber 8 and a spray head 11.

The electrode plate 7 is arranged in the top of the spray chamber 8, andthe spray head 11 is located at the bottom of the spray chamber 8. Theelectrode plate 7 generates the electric field when a bias voltage froman exterior power supply is supplied to the plate 7. Under the effect ofthe electric field, the charged organic gas is driven to spray out fromthe spray head 11 of the spray device 92 so as to form an organic filmon the substrate 13. For example, in this embodiment, the chargedorganic gas Q is driven by the vertically downward electric field forceand moved from the upper portion to the lower portion of the spraychamber 8, then the charged organic gas is sprayed out through the sprayhead 11 to the substrate 13 and form the organic film thereon, as shownin FIG. 3.

The magnitude of the bias voltage provided by the exterior power supplymay be adjusted depending on the situation of the organic filmdeposition. In one example, another electrode plate may be arrangedopposed to the electrode plate 7. Another electrode plate may bedirectly grounded, or may be arranged adjacent to the spray head 11, ormay be arranged under a conveyer of the platform 14. The exterior powersupply may provide a positives or negative bias voltage, which isdepended on the polarity of the charged organic gas (namely, thepolarity of the charge emitted by the electron emission device 7). Ifthe electron emission device 7 emits a positive charge and the polarityof the charged organic gas is also positive, the electrode plate 7should be applied a positive bias voltage to generate a verticallydownward electric field, under which the organic gas with the positivecharge is driven to move downwardly by a downward electric filed force.If the electron emission device 7 emits the negative charge and thepolarity of the charged organic gas is also negative, the electrodeplate 7 should be applied a negative bias voltage to generate avertically upward electric filed, under which the organic gas with thenegative charge is driven to move downwardly by a downward electricfiled force.

In this embodiment, for example, electrode plate 7 may be made ofstainless steel, but is not limited to this material. The size of theelectrode plate 7 is depended on the space of the upper portion of thespray chamber 8. In order to achieve sufficient velocity of the organicgas, it is necessary to design the spray chamber 8 with a long enoughdistance in the vertical direction. In order to improve the uniformityof the film to be formed, it is also necessary to design the chamber 8with a long enough width in the horizontal direction. For example,sidewall 10 of the spray chamber 8 may be made of stainless steel, butis not limited to this material.

This embodiment is not limited to the above embodiment, and may bevariously changed. For example, the number or configuration of theevaporation container, the shape, configuration or size of theevaporation opening, or the size of the spray head mentioned in theabove embodiment may be changed.

The charged organic gas enters the spray chamber 8, whose position andsize is not limited. However, in order to charge the organic gassufficiently and uniformly, the distance between the spray chamber 8 andthe electron gun 5 and the distance between the spray chamber 8 and theevaporation opening 15 should be long enough. In one example, a gaschannel 9 is arranged between the evaporation container 3 and the spraychamber 8. The organic gas evaporated from the evaporation opening 15 ischarged uniformly by the electron “e” emitted from the electron emitterport, and then horizontally moves from the evaporation opening 15 intothe spray chamber 8 through the gas channel 9.

In one example, an insulator 6 may be arranged between the electrodeplate 7 and the spray chamber 8 for electrically isolating the electrodeplate 7 from the spray chamber 8. The material of the insulator 6 is notlimited herein. Under the effect of the vertically downward electricfield force, the charged organic gas Q is accelerated and moveddownwardly to the spray head 11 and then sprayed out.

FIG. 3 is a cross-sectional view schematically illustrating thedepositing of the organic gas sprayed from the spray chamber 8 onto asurface of the substrate 13. A mask may be arranged between the sprayhead 11 and the substrate 13. After being accelerated, the chargedorganic gas passes through the mask 12 and is deposited on the substrateso as to form the organic film. Because the mask 12 is located over thesubstrate 13, the distance between the mask 12 and the platform 14 canbe reduced, thus elastic fatigue and droop caused by thermal expansionand contraction of the large metallic mask can be avoided. Therefore,the deviation of alignment can be eliminated, and the accuracy of thedeposition can be improved accordingly. The horizontal width of thespray chamber 8 is not limited herein, so as to form a large areaorganic film deposition.

It is necessary to provide a relative motion with a constant velocity ina horizontal direction between the apparatus for coating an organic filmand the substrate 13 of this embodiment. FIG. 4 schematicallyillustrates a working state of the apparatus for evaporating organicmaterials. For ensuring the organic material is uniformly coated on theentire substrate, the platform 14 moves at a given velocity “V” belowthe spray head 11. However, the manner of the relative motion betweenthe apparatus and the substrate is not limited to move the platform withrespect to the spray device, it is also feasible to move the spraydevice together with the spray chamber 8 at a given velocity withrespect to the substrate. For achieving a desired thickness of theorganic film, the spray chamber also may be moved in a reciprocatingmode, which is facilitate to realize the mass production for large sizesubstrate or device and improve the utilization of the organic materialand the deposition rate.

In the first embodiment, the linear evaporation used in the apparatusfor coating organic material can improve the utilization of the organicmaterial. By accelerating the organic gas under the effect of theelectric field, the deposition rate can be improved and the productiontime can be reduced, meanwhile, the moving direction of the organic gasis identical and the uniformity of the coated film can be realized.During the spray process, the organic gas moves from top to bottom ofthe spray chamber. By arranging the mask on the substrate, the deviationof alignment which is resulted from the elastic fatigue and the droopcaused by the thermal expansion and contraction can be avoided and theaccuracy of the deposition can be improved. Furthermore, by arrangingthe barrier over the evaporation opening, the evaporation opening can beclosed when the evaporation is not necessary, thus the organic gas cannot be escaped from the container, thereby saving the organic materialand the cost.

Second embodiment

As shown in FIG. 5, the second embodiment of the present inventionprovides a method for coating an organic film, which comprises:

Step S1: heating and evaporating an organic material to generate uniformorganic gas. The step is performed in an evaporation container. Theorganic material, which is uniformly distributed on the bottom of theevaporation container, is gasified by the heat of a heating sourcearranged beneath the evaporation container wall.

In one example, the procedure of step S1 is shown in FIG. 6, whichcomprises:

Step S11: uniformly heating the organic material to generate the organicgas. The heating source, which uniformly heats the organic material, maybe a linear heating source or a plurality of heating sources parallel toeach other.

Step S12: linearly evaporating the organic gas and emitting the uniformorganic gas. For example, the evaporation container is a linearevaporation container, at the top of which a slit-like evaporationopening is arranged, and the organic gas is uniformly exhausted throughthe evaporation opening.

Step S2: uniformly charging the uniform organic gas for obtainingcharged organic gas. This step is carried out at the evaporation openingof the evaporation container.

For example, the electron (also may be a positive charge) is uniformlyemitted by an electron emission device. Because the electron emissiondevice arranged over the evaporation opening of the evaporationcontainer, the electrons emitted from the electron emission device areattached to the uniform organic gas. Therefore, the charged organic gascan be obtained by uniformly charging the uniform organic gas. In themethod of this embodiment, the organic material is charged after itbecomes gas through evaporation. The advantage of this manner is thatthe organic gas is more easily to be charged uniformly, thus a moreuniform organic film sprayed on the substrate can be obtained.

In one example, the charged organic gas moves from the evaporationopening to the spray chamber through a gas channel between theevaporation container and the spray chamber.

Step S3: accelerating and moving the charged organic gas under an effectof an electric field toward a substrate to form an organic film on thesubstrate.

In one example, the process of step S3 is shown in FIG. 7, whichcomprises:

S31: generating the electric field by a potential difference between anelectrode plate arranged in top of the spray chamber and the base of thespray chamber, when a bias voltage being applied by the external powersupply. In this embodiment, the electric filed difference leaded bypotential difference is provided by only one electrode plate rather thantwo electrode plates, which can save the material of the electrode plateand the cost.

S32: after the charged organic gas reaches the spray chamber, downwardlyaccelerating and moving the charged organic gas under an effect of adownward electric field force.

S33: after the charged organic gas reaches the spray head at bottom ofthe spray chamber, spraying the charged organic gas out of the sprayhead. Under the effect of the electric field force, the charged organicgas is moved from top to bottom of the spray chamber. As the organic gasis uniformly charged, it is sprayed out of the spray head uniformlyunder the effect of the uniform electric field force.

S34: depositing the sprayed organic gas which is passed through the maskto form the organic film on the substrate. Because the mask is locatedover the substrate 13, the distance between the mask and the platform 14can be reduced, thus elastic fatigue and droop caused by thermalexpansion and contraction of the large metallic mask can be avoided.Therefore, the deviation of alignment can be eliminated, and theaccuracy of the deposition can be improved accordingly.

In the second embodiment, the linear evaporation used in the filmcoating method can improve the utilization of the organic material. Byaccelerating the organic gas under the effect of the electric field, thedeposition rate can be improved and the production time can be reduced,meanwhile, the moving direction of the organic gas is identical and theuniformity of the coated film can be realized. During the spray process,the organic gas is sprayed from top to bottom of the chamber. Byarranging the mask on the substrate, the deviation of alignment which isresulted from the elastic fatigue and the droop caused by the thermalexpansion and contraction can be avoided and the accuracy of thedeposition can be improved.

In summary, the embodiments of the present invention have modifiedtraditional coating apparatus and provide a new apparatus and method forcoating the organic film. By utilizing the linear evaporation, theorganic gas is uniformly evaporated in the evaporation container. Afterevaporating, the organic gas is charged by the electrons emitted by theelectron emission device and moved into the spray chamber. Under theeffect of the electric filed force generated by the electrode plate, thecharged organic gas is moved downwardly to the spray head from which itis sprayed out. Finally, the sprayed spray organic gas passes throughthe mask and is deposited on the substrate to form the organic film.Compared with the evaporation method in conventional technology, thepresent invention has the following advantages:

(1) The organic gas is charged more uniformly, because the organicmaterial is charged after it becomes organic gas through evaporation andthe evaporated organic gas is charged by the electron emission device(such as the electron gun).

(2) The electric filed is generated by only one electrode plate and theelectrode plate is supplied with a positive or a negative bias voltagefor generating the potential difference, thus the space of the spraychamber and the manufacture cost of the apparatus can be reduced.

(3) The evaporation container and the spray chamber are arrangedseparately, which ensures the uniformity of the organic gas evaporatedfrom the evaporation container and the uniformity of the organic filmformed by spraying process.

What are described above is related to the illustrative embodiments ofthe disclosure only and not limitative to the scope of the disclosure;the scopes of the disclosure are defined by the accompanying claims.

1. An apparatus for coating an organic film, wherein the apparatuscomprises: an evaporation device, an electron emission device and aspray device; wherein said evaporation device comprises an evaporationcontainer, said evaporation container is a linear evaporation container,in which a uniform organic gas is generated; said electron emissiondevice is horizontally arranged over the evaporation container such thatthe organic gas evaporated in the evaporation container is uniformlycharged and becomes charged organic gas; said spray device is providedwith an electric field, under which the charged organic gas is movedtoward a substrate so as to deposit the organic film on the substrate.2. The apparatus according to claim 1, wherein said evaporation devicefurther comprises: a heating source, said heating source is a linearheating source or a plurality of heating sources parallel to each otherand is arranged at bottom of the evaporation container to provideuniform heat for organic material evaporation.
 3. The apparatusaccording to claim 1, wherein said evaporation container comprises aslit-like evaporation opening arranged at top of the evaporationcontainer, said electron emission device comprises an electron emissionport arranged over the evaporation opening.
 4. The apparatus accordingto claim 3, further comprising a movable barrier arranged neighboring tothe evaporation opening for opening or closing said evaporation opening.5. The apparatus according to claim 1, wherein said evaporationcontainer further comprises a cooling pipe arranged around theevaporation container for maintaining the evaporation container at aconstant temperature.
 6. The apparatus according to claim 1, whereinsaid electron emission device is a linear electron gun or a plurality ofsmall-sized electron guns arranged with equal interval, which emitselectrons uniformly.
 7. The apparatus according to claim 1, wherein thespray device comprises an electrode plate, a spray chamber and a sprayhead; wherein said electrode plate is arranged in top of the spraychamber, said spray head is arranged at bottom of the spray chamber; abias voltage provided by an exterior power supply is applied to theelectrode plate and an vertically downward electric field is generated,the charged organic gas is moved under effect of the electric field froman upper portion to an lower portion of the spray chamber and thensprayed out of the spray head.
 8. The apparatus according to claim 7,wherein the magnitude of the bias voltage provided by the exterior powersupply is adjusted depending on situation of the organic filmdeposition.
 9. The apparatus according to claim 7, wherein a gas channelis arranged between said evaporation container and said spray chamber,said charged organic gas is horizontally moved from the evaporationchamber into the spray chamber through the gas channel.
 10. Theapparatus according to claim 7, wherein an insulator is arranged betweenthe electrode plate and the spray chamber.
 11. The apparatus accordingto claim 7, wherein a mask is arranged between the spray head and thesubstrate.
 12. The apparatus according to claim 1, wherein a relativemotion with a constant velocity in a horizontal direction is generatedbetween said apparatus and said substrate.
 13. The apparatus accordingto claim 1, wherein said charged organic gas is sprayed out of the spraydevice from top to bottom.
 14. A method for coating an organic film,wherein the method comprises: heating and evaporating an organicmaterial to generate uniform organic gas; uniformly charging the uniformorganic gas for obtaining charged organic gas; and accelerating andmoving the charged organic gas toward the substrate under an effect ofan electric filed to form the organic film on the substrate.
 15. Themethod according to claim 14, wherein heating and evaporating an organicmaterial to generate uniform organic gas comprises: uniformly heatingthe organic material to generate the organic gas; linearly evaporatingthe organic gas and emitting the uniform organic gas.
 16. The methodaccording to claim 14 or 15, wherein uniformly charging the uniformorganic gas for obtaining charged organic gas comprises: uniformlyemitting electrons and attaching the electrons to the uniform organicgas, such that the uniform organic gas is uniformly charged and thecharged organic gas is obtained.
 17. The method according to any one ofclaims 14 to 16, wherein accelerating and moving the charged organic gastoward the substrate under an effect of an electric filed to form theorganic film on the substrate comprises: generating the electric fieldby a potential difference between an electrode plate arranged in top ofthe spray chamber and base of the spray chamber, when a bias voltagebeing applied by an external power supply; after the charged organic gasreaches the spray chamber, downwardly accelerating and moving thecharged organic gas under an effect of a downward electric field force;after the charged organic gas reaches the spray head arranged at bottomof the spray chamber, spraying the charged organic gas out of the sprayhead; depositing the sprayed organic gas which is passed through a maskto form the organic film on the substrate.
 18. The apparatus accordingto claim 2, wherein said evaporation container comprises a slit-likeevaporation opening arranged at top of the evaporation container, saidelectron emission device comprises an electron emission port arrangedover the evaporation opening.